Method and apparatus for braiding rope



Aug. 15, 1967 w. BETTA METHOD AND APPARATUS FOR BRAIDING ROPE 4 Sheets-Sheet Filed Feb. 1, 1965 A ttorneys Aug. 15, 1967 w. BETTA METHOD AND APPARATUS FOR BRAIDING ROPE 4 Sheets-Sheet Filed Feb. 1, 1965 12 Inventor wal er Belg a a Z TQM/MJ, Attorneys Aug. 15, 1967 w. BETTA METHOD AND APPARATUS FOR BRAIDING ROPE 4 Sheets-Sheet 3 Filed Feb. 1, 1965 lnvenlor Lia/72W Band y Attorneys Aug. 15, 1967 w. BETTA 3,335,634

METHOD AND APPARATUS FOR BRAIDING ROPE Filed Feb. 1, 1965 4 SheetsSheet 4 F/GG Inventor United States Patent 3 335,634 METHOD AND APPAR ATUS FOR BRAIDING ROPE Walter Betta, Bergamo, Italy, assignor to C.R.F. Otiicine Meccaniche di Precisione S.p.A., Milan, Italy Filed Feb. 1, 1965, Ser. No. 429,310 Claims priority, application Italy, Mar. 3, 1964, 4,790/ 64 18 Claims. (Cl. 87-8) In certain types of equipment, for example winches, pulley blocks, hoists, and generally in equipment in which ropes are employed in open loops and are constrained to pass over pulleys or winding drums, it is necessary to employ particularly stable ropes, by which is meant that the characteristics of the ropes should not alter when they change from the loaded to the unloaded condition. It is only in this case, that wear of the ropes is minimized and hence the cost of maintenance of the equipment is reduced.

In the use of these types of equipment experience has shown that the rope that best meets the requirements is one that has braided strands.

This type of rope, which has been known for some years, has not found any use by reason of high cost, which is mainly due to the low output of the machines by which it is made.

At present, commercial braiding machines are based on the principle of causing the spools on which the strands constituting the rope are wound to move along a rail in the form of four circles tangential to one another and having their centers disposed at the corners of a square. At the tangent points of the guide formed by the circles are provided change-over devices that permit the supporting carriages of the spools to pass from one circle to another. Actuall-y, each carriage does not completely traverse all four circles, but only that part of each of them that permits them to follow a path which is substantially of figure 8 form, with its axis along one of the diagonals of the above mentioned square.

The movement of the carriages along the guide is such that, of the carriages, which are generally eight in number, half of them follow a path along one diagonal and the other half along the other diagonal. Furthermore, the carriages are staggered along the guide in such manner that each change-over device is passed alternatively by a carriage from one path and a carriage from the other path.

Since the spool imparts tension to the rope while it follows the curved part of the rail, it imparts tension to the rope, before the braiding is effected it is caused to rotate by means of a clamp, also of known type, in such manner as to relieve the torsion that has been set up.

A braiding machine that operates on this principle cannot attain any appreciable speed, and hence high production, for two important reasons:

(a) The machine is always unbalanced and hence subjected to alternate forces, and (b) the torsion relieving mechanism has a jerky movement and is very primitive.

The braiding apparatus and method according to the present invention is based on a braiding principle which enables production to be increased to the extent of substantially approaching the output of machines for making helically wound ropes.

The said principle results from the observation that for the purpose of braiding two interconnected strands with a spacer it is sufficient to cause the spacer to rotate through 180 about its center.

In the apparatus and method according to the present invention there are provided spools on which are wound the strands intended to form the rope, mounted on spindles movable along predetermined paths. The principal feature of the present arrangement is that it provides at least three spools which follow, at uniformly spaced positions, a circular path, and at least three other spools which follow, in contrary sense to the first spools and at similarly spaced positions, an elliptical path, the two paths having coincident centers and. being traversed in equal times.

In accordance with a preferred embodiment of the invention, the eight spools are provided on which the strands are wound. Four of these spools describe an ellipse and the other four describe a circle. The four spools that describe the circle maintain uniformly spaced positions along the said circle, substantially at the ends of two perpendicular diameters. The other four spools that describe the ellipse pass simultaneously through the ends of the two principal axes, but these do not maintain uniform spacings along the ellipse, as will be explained below.

The invention will now be described in more detail with reference to the accompanying drawings which illustrate an embodiment of the invention by way of example.

In the drawings:

FIG. 1 illustrates diagrammatically the guide of a known arrangement for controlling eight spools,

FIG. 2 is a diagram similar to that of FIG. 1 but relating to the arrangement according to the present invention, in which eight spools are also used,

FIG. 3 is a diagram showing the course of the strands that constitute a rope made by the devices shown in FIGS. 1 and 2,

FIG. 4 is a diagrammatic side view partly in section, of the apparatus according to the present invention for controlling eight spools,

FIGS. 5 and 6 are diagrammatic plan views of the apparatus shown in FIG. 4, illustrating separately the two groups of four spools that follow circular and elliptical paths respectively.

As shown in FIG. 1, in the known arrangements there is provided a guide 1 in the form of four tangent circles on which can run carriages each carrying a spool 2 wound with a strand for use in the formation of the rope. The carriages traverse the guide 1 along two paths indicated respectively by dotted lines and broken lines, substantially in accordance with the two diagonals of the square having corners at the centers of the circles of the guide 1. These circles are traversed by the spool carrying carriages in the directions indicated by the arrows. The spools that follow one path are indicated by a, b, c, d, and those that follow the path at right angles by e, f, g, h. The relative position of the spools in the two paths is such, for example, that due to the change-over device 1 the spools follow the sequence, d, c, b, a, thereby producing the required braiding of the strands to form the rope. The form of braiding executed by this machine is substantially as illustrated in FIG. 3 on a much enlarged scale.

FIG. 2 illustrates the principle underlying the arrangement according to the present invention. Pour carriages 3 follow a circular path 4, while four other carriages 5 follow an elliptical path 6. The paths are traversed in opposite directions-for example one in a clockwise direction and the other in a counterclockwise directionand each spool assumes the position of the preceding one after rotation. The rope produced in this manner is again braided exactly as shown in FIG. 3.

It will at once be seen by comparing the principle of operation of the arrangement according to the invention with the principle of a conventional apparatus, that for equal angular velocities the output of the present apparatus is double that of the traditional apparatus. In fact, while it can be considered that in accordance with the present invention eight spools traverse a complete .path

after four traverses each of 90, or after 360, in the machine of known type the spools traverse a complete path only after eight traverses of 90 (eight times a quarter of a circle) or after double the angular path. It is clear from an examination of the path that in the machine of known type it is equivalent to two complete circles for each spool.

In the latter regard, reference is made to FIG. 1 which depicts the prior art arrangement and includes two figure eight movements of the respective spools. Specifically, spools a, b, c, of travel in a figure eight direction depicted by the broken lines of FIG. 1, while spools e, f, g, 12 travel in a similar manner along the path indicated by the dotted lines of FIG. 1. It is thus apparent that a given spool on either of said paths must travel the equivalent of 720 in order to complete a single cycle. In comparison, a reference to FIG. 2 of the drawings will reveal that, in the present invention, a given spool on either of the paths 4 or 6 will complete a full cycle in 360 or in half the distance that a corresponding spool of the prior art requires to complete a cycle.

The double path as illustrated in FIG. 2 may of course be followed by providing suitable guides and carriages, but in accordance with the present invention the problem is solved in a much more satisfactory manner.

'In FIGS. 4 to 6 a preferred embodiment of the apparatus according to the present invention is illustration in more detail.

FIG. 6 shows the mechanism which moves the four spools 2 that describe the elliptical path. It is constituted by a cross piece 7 on each extremity of which is rotatably mounted a gear wheel 8 which is solid with the pivot of an arm 9 on the end of which is carried a spool 2. The four gear wheels 8 engage with pinions 10, which in turn engage with a toothed wheel 11, the overall transmission ratio between the wheel 11 and the spool carrying arm 9 being equal to two. To the cross member is imparted a rotation about the axis ZZ (see also FIG. 4), the toothed wheel 11 being fixed.

From consideration of FIG. 6 with reference to passage from position a to position b, it will be seen that while the cross member completes a rotation of 90 the spool carrying arm 9 rotates through 180 about its pivot, and hence the spool passes from the interior to the exterior of the circumference of the gear wheel 8. This is possible since, due to the movement of the cross-piece 7, arm 9 is caused to pivot about the end of piece 7 due to the engagement of gear 8 with pinion 10. This pivotal movement causes the spool 2 located on the end of arm 9 to move from a position outwardly from gear 8 as shown in the bottom portion of FIG. 6. Thus as arm 7 completes a 360 movement, a given spool will have movement in an elliptical path as shown in FIG. 2. This elliptical path, however, is not traversed with uniform motion, the spools undergoing acceleration in the zones near the ends of the minor axes, and conversely being retarded in the zones near the ends of the major axes. In every case, however, the spools in the elliptical path complete a quarter of their path, viz. the distance comprised between the end of one axis and the end of the other axis, in a time which is always equal and exactly corresponds to the time required by the spools of circular path for completing an arc of 90.

Hence it is clear that when the cross member has completed one full revolution the spool will have described an ellipse having conjugate axes of length x and y indicated in FIG. 6.

The axes of rotation of the gear wheels 8 are inclined, and converge towards a common point on the vertical axis ZZ of the machine, which always cor-responds to the point of formation of the braided rope. The gear Wheels 8 and the toothed wheel 11, as well as the pinions 10, preferably have correspondingly convergent bevelled teeth. The main object of this construction is to enable the spools to be maintained, during the elliptical motion,

at a substantially constant distance from the point of formation of the braid.

During the movement, each spool is caused to rotate about its axis, by means of a series of gear wheels 12, 13 and 14, the gear wheel 12 being coaxial with the gear wheel '8 and solid with the cross member 7. The trans mission ratio of the gear wheels 12, 13 and 14 is such that the spool executes a rotation opposite to that of the cross member, in such manner as to prevent the occurrence of torsion in the rope.

FIG. 5 shows the mechanism that moves the four spools 2 that describe a circle. They move on two guide members 15 and 16 of circular arcuate form, supported so as to overhang the frame. The guide members are arranged in such manner as not to interfere with the motion of the mechanism that moves the other four spools. They move, in fact, in a plane which is advanced in the direction of the braiding point of the rope relative to the medial plane of the mechanism that moves the other four spools, and they are moreover spaced from one another so as to provide between them passages 17 and 18 for the strands coming from the spools that describe the ellipse. The axes 2 of the four spools of circular path move on the guides via carriages 19 which are supported on the guides 15 and 16 which for this purpose are substantially of T-section. In the central part facing the guide the carriages have teeth 19' with which, engage pinions 20 which for this purpose, extend across openings 21 suitably provided in the guides 15 and 16. The pinions 20 are uniformly spaced along the guides 15 and 16, and their spacing is less than the amplitude of the teeth 19', so that the carriages 19 are always caused to advance by at least one pinion 20, even during passage from one guide member to the other across the passages 17 and 18. In turn, the pinions 20 are controlled in pairs by gear wheels 22 which are rotated by a large toothed wheel 23 via reduction gearings 24.

The mechanism for moving the spools along the circular path is of course synchronized with that for moving the spools along the elliptical path, in such manner that there is no interference with the interlacing of the relative strands.

The four spools that describe the circle are, like the others, provided with a mechanism that prevents the occurrence of torsion in the rope. This mechanism is constituted by a pair of pinions 25 mounted on each shoe 19, which are set in rotation due to the motion of the associated shoe by gear teeth 15 and 16 associated with the two guide members 15 and 16, and they transmit motion to gear Wheels 26 solid with the spindles of the spools. This motion is transmitted as in the case of the spools with elliptical motion, in such a manner that, during the rotation, no torsion occurs in the strands that are to form the braid.

A device of a known type (not illustrated) is provided for collecting the finished rope. It is preferably controlled, via suitable reduction gearing, by the motor that controls the rotation of the present apparatus.

What I claim is:

1. A method of braiding a rope comprising the steps of moving a first set of spools of strands at uniformly spaced positions along a circular path, moving a second set of spools in an elliptical path coaxial with said circular path, feeding the strands from said spools to a braiding point external of said paths, and synchronizing the movement of said spools to interlace said strands at said braiding point.

2. The method of claim 1, wherein said second set of spools are spaced apart so that they simultaneously pass through positions corresponding to the ends of the conjugate axes of the ellipse.

3. The method of claim 1, wherein said second set of spools is moved in a direction opposite to the movement of said first set of spools.

4. The method of claim 1, wherein each of said paths is traversed in the same time.

5. A device for forming braided ropes, said device comprising two sets of spools of strands, means to move one of said sets of spools along a circular path, means to move said other set of spools along an elliptical path coaxial with said circular path, means to feed the strands from their spools to a common braiding point external of said paths, the axis of each of said paths being in alignment with said braiding point.

6. The device of claim 5, wherein the spools that move along the circular path are uniformly spaced apart, and the spools that move along the elliptical path are spaced apart so that they simultaneously pass through positions corresponding to the ends of the conjugate axes of the ellipse.

7. The device of claim 5, wherein said first set of spools moves in an opposite direction to the movement of said second set of spools.

*8. The device of claim 5, wherein each of said paths is traversed in the same time.

9. A device for forming a braided rope, said device comprising a first circular support member, a first set of spools of strands mounted on the outer portion of said first support member, means to rotate said spools in a circular path about the axis of said support member, a second circular support member extending parallel to and coaxial with said first support member, a second set of spools of strands, means mounting said second set of spools outwardly from said second support member, means to rotate said second set of spools in an elliptical path about the axis of said second support member, and means to feed the strands from their spools to a braiding point external of said paths to interlace said strands.

10. The device of claim 9, wherein the spools of the first set are uniformly spaced with respect to their corresponding support member, and wherein the spools of the second set are spaced apart so that they simultaneously pass through positions corresponding to the ends of the conjugate axes of the ellipse.

11. The device of claim 9, wherein said first set of spools moves in an opposite direction to the movement of said second set of spools.

12. The device of claim 9, wherein each of said paths is traversed in the same time.

13. The device of claim 9, wherein said elliptical path is substantially the locus of points equidistant from said braiding point.

14. The device of claim 9, wherein said first support member extends between said braiding point and said second support member.

15. The device of claim 9, wherein said first support member comprises a substantially circular guide formed by two parts spaced from one another sufiiciently to permit the free passage of strands from said second set of spools.

16. The device of claim 9, wherein said mounting means comprises a cross member, an arm pivotally mounted on each end of said cross member, each spool of said second set being mounted on a corresponding arm.

17. The device of claim 16, wherein said means to rotate said second set of spools comprises a drive means for rotating said cross member about the axis of said second support member, and gearing means connected to each of said arms for pivoting same about the end of their corresponding cross member in response to retation of said cross member.

18. The device of claim 16, wherein the axes of rotation of said arms are inclined with respect to said second support member and converge toward the axis thereof.

References Cited UNITED STATES PATENTS 473,369 4/1892 Spaulding et al. 87-50 X 1,513,398 10/1924 King 875 0 2,085,334 6/1937 Richards 875 0 X FRANK I. COHEN, Primary Examiner.

J. PETRAKES, Assistant Examiner. 

1. A METHOD OF BRAIDING A ROPE COMPORISING THE STEPS OF MOVING A FIRST SET OF SPOOLS OF STRANDS AT UNIFORMLY SPACED POSITIONS ALONG A CIRCULAR PATH, MOVING A SECOND SET OF SPOOLS IN AN ELLIPTICAL PATH COAXIAL WITH SAID CIRCULAR PATH, FEEDING THE STRANDS FROM SAID SPOOLS TO A BRAIDING POINT EXTERNAL OF SAID PATHS, AND SYNCHRONIZING THE MOVEMENT OF SAID SPOOLS TO INTERLACE SAID STRANDS AT SAID BRAIDING POINT.
 5. A DEVICE FOR FORMING BRAIDED ROPES, SAID DEVICE COMPRISING TWO SETS OF SPOOLS OF STRANDS, MEANS TO MOVE ONE OF SAID SETS OF SPOOLS ALONG A CIRCULAR PATH, MEANS TO MOVE SAID OTHER SET OF SPOOLS ALONG AN ELLIPTICAL PATH COAXIAL WITH SAID CIRCULAR PATH, MEANS TO FEED THE STRANDS FROM THEIR SPOOLS TO A COMMON BRAIDING POINT EXTERNAL OF SAID PATHS, THE AXIS OF EACH OF SAID PATHS BEING IN ALIGNMENT WITH SAID BRAIDING POINT. 